The temporal bone, os temporale, the paired bone has a complex structure, since it performs all 3 functions of the skeleton and not only forms part of the lateral wall and base of the skull, but also contains the organs of hearing and gravity. It is the product of the fusion of several bones (mixed bone) that exist independently in some animals, and therefore consists of three parts:
1) scaly part, pars squamosa;
2) the drum part, pars tympanica and
3) rocky part, pars petrosa.
During the 1st year of life, they merge into a single bone, closing external auditory canal, meatus acusticus externus, in such a way that the scaly part lies above it, the stony part is inward from it, and the tympanic part is behind, below and in front. Traces of the fusion of individual parts of the temporal bone remain for life in the form of intermediate sutures and cracks, namely: on the border of pars squamosa and pars petrosa, on the anteroposterior surface of the latter - fissura petrosquamos a; deep in the mandibular fossa - fissura tympanosquamosa, which is divided by the process of the stony part into fissura petrosquamosa and fissura petrotympanica(the chorda tympani nerve comes out through it).
Scaly part, pars squamosa, participates in the formation of the lateral walls of the skull. It belongs to the integumentary bones, that is, it ossifies on the soil of connective tissue and has a relatively simple structure in the form of a vertically standing plate with a rounded edge overlapping the corresponding edge of the parietal bone, margo squamosa, in the form of fish scales, hence its name.
On its cerebral surface, facies cerebralis, traces of the brain are visible, digital impressions, impressiones digitatae, and ascending to the top groove from a. meningea media... The outer surface of the scales is smooth, participates in the formation of the temporal fossa (the anatomy of which is considered) and therefore is called facies temporalis.
Departs from her zygomatic process, processus zygomaticus, which goes forward to the junction with the zygomatic bone. At its beginning, the zygomatic process has two roots: anterior and posterior, between which there is a fossa for articulation with the lower jaw, fossa mandibularis.
On the lower surface of the anterior root is placed articular tubercle, tuberculum articulare, preventing the dislocation of the head of the lower jaw forward with a significant opening of the mouth.
Drum part, pars tympanica, the temporal bone forms the anterior, lower and part of the posterior edge of the external auditory canal, ossifies endesmally and, like all integumentary bones, has the form of a plate, only sharply curved.
External auditory canal, meatus acusticus externus, is a short channel going inward and somewhat forward and leading to the tympanic cavity. The top edge of it external opening, porus acusticus externus, and part of the posterior edge is formed by the scales of the temporal bone, and on the rest of the length - by the tympanic part.
In a newborn, the external auditory canal has not yet been formed, since the tympanic part is an incomplete ring (annulus tympanicus), tightened by the tympanic membrane. Due to such a close location of the tympanic membrane outwards, diseases of the tympanic cavity are more often observed in newborns and young children.
The stony part, pars petrosa, is so named for the strength of its bone substance, due to the fact that this part of the bone participates in the base of the skull, and is the bony receptacle of the organs of hearing and gravity, which have a very thin structure and need strong protection from damage. It develops on the basis of cartilage. The second name of this part is a pyramid, given by its shape of a triangular pyramid, the base of which is turned outward, and the top - forward and inward to the sphenoid bone.
The pyramid has three surfaces: front, back and bottom. The anterior surface is part of the bottom of the middle cranial fossa; the posterior surface faces posteriorly and medially and forms part of the anterior wall of the posterior cranial fossa; the lower surface faces downward and is visible only on the outer surface of the skull base. The external relief of the pyramid is complex and due to its structure as a receptacle for the middle (tympanic cavity) and inner ear (bony labyrinth, consisting of the cochlea and semicircular canals), as well as the passage of nerves and blood vessels.
On the front surface of the pyramid, near its apex, a slight depression is noticeable, impressio trigemini, from the node of the trigeminal nerve (n. trigemini,). Outside of him pass two thin grooves, medial - sulcus n. petrosi majoris, and lateral - sulcus n. petrosi minoris... They lead to two similar holes: medial, hiatus candlis n. petrosi majoris, and lateral, hiatus canalis n. petrosi minoris. Outwardly from these holes, an arcuate elevation is noticeable, eminentia arcuata, formed due to the protrusion of a rapidly developing labyrinth, in particular the upper semicircular canal.
Bone surface between eminentia arcuata and squama temporalis forms the roof of the tympanic cavity, tegmen tympani.
Approximately in the middle of the back surface of the pyramid is internal auditory opening, porus acusticus internus which leads to internal auditory canal, meatus acusticus internus where the facial and auditory nerves, as well as the artery and veins of the labyrinth pass.
From the lower surface of the pyramid, facing the base of the skull, a thin pointed styloid process, processus styloideus serving as the site of muscle attachment "Anatomical bouquet"(mm. styloglossus, stylohyoideus, stylopharyngeus), as well as ligaments - ligg. stylohyoideum and stylomandibular. The styloid process is a part of the temporal bone of the branchial origin. Together with lig. stylohyoideum it is the remainder of the hyoid arch.
Between the styloid and mastoid processes there is styloid foramen, foramen stylomastoideum through which n comes out. facialis and a small artery enters. Medially from the styloid process is a deep jugular fossa, fossa jugularis... Anterior to the fossa jugularis, separated from it by a sharp ridge, is the outer opening of the sleepy canal, foramen caroticum externum.
The pyramid has three edges: front, back and top. The short anterior margin forms an acute angle with scales. In this corner it is noticeable about muscular tube opening, candlis musculo tubarius leading to the tympanic cavity. This canal is divided by a partition into two sections: upper and lower. Upper, smaller, half-channel, semicanalis m. tensoris tympani, contains this muscle, and the lower, larger, semicandlis tubae auditivae, represents the bony part of the auditory tube, which serves to conduct air from the pharynx into the tympanic cavity.
Along the upper edge of the pyramid, dividing the anterior and posterior surfaces, there is a clearly visible groove, sulcus sinus petrosi superiors, - the trace of the venous sinus of the same name.
Rear edge of the pyramid anterior to the fossa jugularis connects with the basilar part of the occipital bone and forms together with this bone sulcus sinus petrosi inferioris- trace of the inferior petrosal venous sinus.
The outer surface of the base of the pyramid serves as a place of muscle attachment, which determines its external relief (process, notches, roughness). From the bottom it stretches into mastoid process, processus mastoideus... Attached to it is the sternocleidomastoid muscle, which supports the head in the balance required when the body is upright. Therefore, the mastoid process is absent in tetrapods and even apes and develops only in humans in connection with his upright posture.
On the medial side of the mastoid process there is a deep mastoid notch, incisura mastoidea, - the place of attachment m. digastricus; even more inward - a small furrow, sulcus a. occipitalis, - a trace of the artery of the same name.
On the outer surface of the base of the mastoid process, a smooth triangle is distinguished, which is a place for prompt access to the cells of the mastoid process when they are filled with pus.
Inside the mastoid process and contains these cell cellulae mastoideae, which are air cavities separated by bone bars, receiving air from the tympanic cavity, with which they communicate through antrum mastoideum... On the cerebral surface of the base of the pyramid passes deep furrow, sulcus sinus sigmoidei where the venous sinus of the same name lies.
Temporal bone canals. The largest channel is canalis caroticus through which the internal carotid artery passes. Starting with its outer opening on the lower surface of the pyramid, it rises upward, then bends at a right angle and opens with its inner opening at the apex of the pyramid medially from canalis musculotubarius.
Facial canal, canalis facialis, starts at the bottom porus acusticus internus from where the canal first goes forward and laterally to the cracks (hiatus) on the anterior surface of the pyramid; at these holes, the canal, while remaining horizontal, turns at right angles laterally and backward, forming a bend - knee, geniculum canalis facialis, and then down and ends by means of the foramen stylomastoideum, located on the lower surface of the pyramid of the temporal bone, canalis musculotubarius.
Video # 1: normal anatomy of the temporal bone of the skull
Other video tutorials on this topic are:Video # 2: normal anatomy of the temporal bone canals
The temporal bone, os temporale, is a paired, complex in shape and structure bone that participates in the formation of the base of the skull, located between the occipital and sphenoid bones, and also complements the lateral walls of the cranial roof. It distinguishes three parts located around the external auditory opening: scaly, tympanic and stony.
The scaly part, pars squamosa, is a vertically located bone plate. With a free, uneven, obliquely cut edge, it connects through a scaly suture with the lower edge of the parietal bone and with the large wing of the sphenoid bone. At the bottom, the scaly part adjoins the stony and tympanic parts and is separated from it by a stony-scaly fissure, fissura petrosquamosa (visible only on the bones of young subjects), and from the tympanic part - a drum-scaly fissure, fissura tympanosquamosa.
The outer temporal surface, facies temporalis, of the scaly part is smooth, participates in the formation of the temporal fossa. Near the lower edge, the zygomatic process, processus zygomaticus, departs from it, directed anteriorly, where it connects with the temporal process of the zygomatic bone and forms a zygomatic arch, arcus zygomaticus. The zygomatic process departs with two roots, between which the mandibular fossa, fossa mandibularis, is formed. It is covered with cartilage and articulates with the articular process of the lower jaw. The anterior root of the zygomatic process, thickening anterior to the mandibular fossa, forms an articular tubercle, tuberculum articulare. On the posterior root of the zygomatic process is a similar articular tubercle, tuberculum retroarticulare, less pronounced. Posteriorly, it passes into the temporal line, linea temporalis.
The inner cerebral surface, facies cerebralis, of the scaly part is equipped with cerebral eminences, digital impressions, as well as grooves of the vessels of the meninges.
Drawing: Temporal bone, right, outside view.
1 - zygomatic process; 2 - articular tubercle; 3 - mandibular fossa; 4 - stony-tympanic fissure; 5 - subulate process; 6 - drum part; 7 - external auditory opening; 8 - the edge of the drum part; 9 - mastoid process; 10 - mastoid opening; 11 - temporal line; 12 - scaly part.
The tympanic part, pars tympanica, is concentrated around the external auditory canal, meatus acusticus externus. In newborns, it is expressed in the form of a ring, anulus tympanicus, open upward and surrounding the external auditory canal. In the future, it grows and merges with neighboring parts. In adults, the tympanic part restricts from below and behind the external auditory opening, porus acusticus externus, and the tympanic cavity, cavum tympani, fused with the free edge with the scales and the mastoid part. It is separated from the scales by a drum-scaly slit, into which the process of the tympanic roof enters from the side of the front surface of the pyramid, due to which the named slit is divided into two parallel slits: stony-scaly, fissura petrosquamosa, and stony-tympanic, fissura petrotympanica, through which from the tympanic a branch of the facial nerve passes through the cavity - the tympanic string, chorda tympani. The cartilaginous part of the ear canal is attached to the free rough and curved edge of the tympanic part, which limits the external auditory opening.
Above the external auditory opening, the supraspinous spine, spina supra meatum, rises.
The stony part, pars petrosa, or pyramid, resembles a three-sided pyramid in shape, the base of which is turned posteriorly and laterally, the apex is anteriorly and medially. Three surfaces are distinguished on the pyramid, of which the front, facies anterior, and the back, facies posterior, face the cranial cavity, and the lower, facies inferior, is part of the outer surface of the skull base. The surfaces are separated by three edges: top, back and front. The base of the pyramid is spliced with the scaly part. A small section of the base of the pyramid, facing outward, remains uncovered and contains the external auditory opening. The pyramid of the temporal bone contains most of the elements of the hearing organs: the bony part of the external auditory canal, the middle and inner ear.
On the front surface of the pyramid there is an arcuate eminence, eminentia arcuata, corresponding to the anterior semicircular canal of the labyrinth of the inner ear. In front of this elevation are two thin grooves: large and small stony nerves, sulci n. retrosi majoris et n. petrosi minoris, ending in the front with the same crevices, hiatus canalis n. petrosi majoris et hiatus canalis n. petrosi minoris. Nerves exit through these holes. The lateral part of this surface of the bone, lying between the arcuate eminence and the scaly-stony fissure, constitutes the upper wall of the tympanic cavity and is therefore called the tympanic roof, tegmen tympani. Near the top of the pyramid there is a trigeminal depression, impressio trigemini. A groove of the upper petrosal sinus, sulcus sinus petrosi superioris, runs along the upper edge of the pyramid. On the back surface of the pyramid there is an internal auditory opening, porus acusticus internus, leading to the internal auditory canal, meatus acusticus internus. Behind the internal auditory opening, the external opening of the vestibule aqueduct, apertura externa aqueductus vestibuli, through which the ductus endolymphaticus passes. At the upper edge of the pyramid, between the internal auditory opening and the external opening of the water supply system of the vestibule, there is a subarc fossa, fossa subarcuata, which reaches large sizes in children, and significantly decreases in adults. At the lower edge, at the level of porus acusticus internus, there is an opening of the snail tubule, apertura externa canaliculi cochleae. Along the posterior edge of the pyramid there is a groove of the lower stony sinus, sulcus sinus petrosi inferioris. The lower surface of the pyramid is uneven. From it, the styloid process descends and forward, the processus styloideus is the place of muscle attachment. The process reaches its full development in the elderly. It is composed of several segments that ossify separately and merge rather late. Between the styloid and mastoid processes under the external auditory opening is the stylo-mastoid opening, the foramen stylomastoideum, which serves as the exit site of the facial nerve. In front and medially of the styloid process is the jugular fossa, fossa jugularis. At the bottom of this fossa, you can see the opening of the mastoid canaliculus, canaliculus mastoideus. In front of the jugular fossa is the external opening of the carotid artery canal, foramen caroticum externum, leading to the carotid artery canal, canalis caroticus, which opens at the top of the pyramid with an internal outlet, foramen caroticum internum. On the back wall of the carotid canal near the external opening there are several small openings of the carotid tubules, canaliculi caroticotympanici, opening into the tympanic cavity and conducting vessels and nerves. In the crest between the external opening of the carotid canal and the jugular fossa, a petrous dimple, fossula petrosa, is distinguished, at the bottom of which the tympanic tubule begins for the nerve of the same name. Laterally from the foramen caroticum internum, in the depth of the angle formed by the scales and the anterior edge of the pyramid, the inlet of the musculocutaneous canal, canalis musculotubarius, divided by an incomplete bony septum into two semicanals is determined: for the muscle straining the tympanic membrane, semicanalis m. tensoris tympani, auditory tube, semicanalis tubae auditivae.
Drawing: Right temporal bone, inside and back view.
1 - arcuate elevation; 2 - parietal margin; 3 - roof of the tympanic cavity; 4 - groove of the superior stony sinus; 5 - sigmoid sinus groove; 6 - mastoid opening; 7 - occipital margin; 8 - subulate process; 9 - furrow of the lower stony sinus; 10 - the top of the pyramid; 11 - rocky part, or pyramid; 12 - zygomatic process; 13 - wedge-shaped edge; 14 - arterial groove; 15 - the back surface of the pyramid; 16 - internal auditory opening.
The base of the pyramid is extended downward into the mastoid process, processus mastoideus, the outer surface of which is rough due to the attachment of the sternocleidomastoid muscle to it. Inside the mastoid process there are cells, cellulae mastoidei, of various shapes and sizes, lined with a mucous membrane. The largest cell is the mastoid cave, antrum mastoideum, which communicates with the middle ear cavity. Inside of the apex of the mastoid process, there are two parallel grooves. The groove of the occipital artery, sulcus a, passes medially. occipitalis, and laterally - the mastoid notch, incisura mastoidea, which is the site of the beginning of the digastric muscle. From the tympanic part, the mastoid process is separated by the tympanic-mastoid fissure, fissura tympanomastoidea, through which the auricular branch of the vagus nerve passes. In the suture between the mastoid and the occipital bone is the mastoid opening, foramen mastoideum. On the outer surface of the mastoid process, a practically important area is distinguished - the mastoid triangle, which is bounded in front by a line drawn from the spina supra meatum (see the chapter "Temporal bone") to the apex of the mastoid process, behind - by the line of attachment of the sternocleidomastoid muscle and from above - a line that is a continuation of the lower edge of the zygomatic process. The triangle serves as a place for trepanation in inflammatory processes of the middle ear.
On the inner surface of the mastoid process there is an S-shaped curved groove of the sigmoid sinus, sulcus sinus sigmoidei. A mastoid opening opens approximately in the middle of its length.
Temporal bone canals. 1. The canal of the facial nerve, canalis facialis, begins at the bottom of the internal auditory canal and goes forward and laterally to the level of the clefts of the canals of the petrosal nerves. From here, at a right angle, it goes laterally and backward, forming a bend - a knee, geniculum canalis facialis, changes direction from horizontal to vertical and ends with an stylo-mastoid opening.
2. Canal of the carotid artery, canalis caroticus (described in the text).
3. Muscular-tubal canal, canalis musculotubarius.
4. The canaliculus of the drum string, canaliculus chordae tympani, starts from the facial canal slightly above the awl-mastoid opening and ends in the area of fissura petrotympanica. A branch of the facial nerve - the drum string - passes through it.
5. Mastoid tubule, canaliculus mastoideus, originates at the bottom of the jugular fossa and ends in the tympanic-mastoid fissure. A branch of the vagus nerve passes through this tubule.
6. The tympanic tubule, canaliculus tympanicus, arises in the fossula pеtrosa with the opening of the apertura inferior canaliculi tympanici, through which the branch of the lingopharyngeal nerve enters, n. tympanicus. Having passed through the tympanic cavity, this nerve called n. petrosus superficialis minor exits through the upper opening of the canal, located on the front surface of the pyramid.
Drawing: Right temporal bone, bottom view.
1 - articular tubercle; 2 - mandibular fossa; 3 - stony-tympanic fissure; 4 - drum part; 5 - mastoid process; 6 - mastoid notch; 7 - muscular-tubal canal; 8 - internal carotid opening; 9 - external carotid opening; 10 - jugular fossa; 11 - awl-mastoid opening; 12 - groove of the occipital artery.
7. Carotid tubules, canaliculi caroticotympanici, pass in the wall of the carotid artery canal near its external opening and open into the tympanic cavity. They serve for the passage of blood vessels and nerves.
Ossification. The temporal bone has 6 ossification points. At the end of the 1st month of intrauterine development, ossification points appear in the scales, at the 3rd month - in the tympanic part. At the 5th month, several points of ossification appear in the cartilaginous anlage of the pyramid. By the time of birth, the temporal bone consists of three parts: scaly with the rudiment of the zygomatic process, stony with the rudiment of the mastoid and the tympanic, which are mostly already connected, but the newborn still has gaps filled with connective tissue between them. The styloid process develops from two centers. The upper center appears before birth and merges with the stony part during the 1st year of life. The lower center appears after birth and merges with the upper center only after the onset of puberty. During the 1st year of life, three parts of the bone grow together.
Temporal bone(os temporale) is a receptacle for the organs of balance and hearing. The temporal bone, connecting with the zygomatic, forms a zygomatic arch (arcus zygomaticus). The temporal bone consists of three parts: scaly, tympanic and petrous.
Scaly part(pars squamosa) of the temporal bone has an external smooth temporal surface (facies temporalis), on which the groove of the middle temporal artery (sulcus arteriae temporalis mediae) passes. From this part (just above the external auditory canal), the zygomatic process (processus zygomaticus) begins, at the base of which is the mandibular fossa (fossa mandibularis). In front, this fossa is limited by the articular tubercle (tuberculum articulare). On the inner cerebral surface (facies cerebralis) there are finger-like impressions and arterial grooves.
Drum part(pars tympanica) of the temporal bone is fused with its edges with the mastoid process and the scaly part, limiting the external auditory opening (porus acusticus externus) on three sides, the continuation of which is the external auditory meatus (meatus acusticus externus). Behind, at the site of the fusion of the tympanic part with the mastoid process, a tympanic-mastoid fissure (fissura tympanomastoidea) is formed. In front of the auditory opening there is a drum-scaly fissure (fissura tympanosquamosa), which is divided by the edge of the roof of the tympanic cavity into a stony-scaly (fissura petrosquamosa) and stony-tympanic fissure (fissura petrotympanica).
Rocky part, or pyramid(pars petrosa), the temporal bone has the shape of a triangular pyramid. In the pyramid, the apex (apex partis petrosae), the anterior, posterior and lower surfaces, the upper and posterior edges and the mastoid process are distinguished.
Temporal bone canals.
The anterior surface of the temporal bone from the lateral side passes into the medullary surface of the squamous bone, from which it is separated by a stony-squamous fissure (fissura petrosquamosa). Next to the stony-scaly fissure lies the opening of the musculocutaneous canal (canalis musculotubaris), which is divided by a septum into two half-channels. One of them is the semi-canal of the auditory tube, and the other is the muscle that strains the eardrum.
In the middle of the anterior surface of the temporal bone there is an arcuate eminence (eminencia arcuata), between it and the stony-scaly gap is the roof of the tympanic cavity (tegmen tympani). Near the apex of the anterior surface there is a trigeminal depression, lateral from which is the opening of the canal of the large stony nerve (hiatus canalis nervi petrosi majoris), from which the groove of the same name begins. Lateral to this canal is the opening of the canal of the small stony nerve, from which the groove of the same name departs.
In the middle of the posterior surface of the temporal bone pyramid is the internal auditory opening (porus acusticus internus), which passes into the internal auditory canal. Lateral to this opening lies a subarc fossa (fossa subarcuata), below and lateral to which there is an external opening of the aqueduct of the vestibule (apertura externa aqueductus vestibuli).
The lower surface of the pyramid of the temporal bone has a jugular fossa (fossa jugularis) at the base, on the front wall of which there is a groove ending in a mastoid opening (foramen mastoideus). The posterior wall of the jugular fossa is represented by the notch of the same name. This notch and the notch of the occipital bone form the foramen jugulare. In front of the jugular fossa, the carotid canal (canalis caroticus) begins, in the wall of which there are small fossa continuing into the carotid-tympanic tubules. On the ridge separating the jugular fossa and the external opening of the carotid canal, there is a petrous dimple (fossula petrosa), at the bottom of which the lower opening of the tympanic tubule opens. Lateral to the jugular fossa, the styloid process (processus styloideus) begins, behind which there is a styloid opening (foramen stylomastoideum).
The upper edge of the temporal bone pyramid separates the anterior surface from the posterior one, and the groove of the superior stony sinus (sulcus sinus petrosi superioris) runs along its surface.
The posterior edge of the pyramid of the temporal bone separates the posterior and lower surfaces, along it there is a groove of the lower stony sinus (sulcus sinus petrosi inferioris).
The mastoid process (processus mastoideus) of the temporal bone from above is separated from the scaly part by the parietal notch (incisura parietalis), from below the process is bounded by the mastoid notch (incisura mastoidea). Medial to the latter is the groove of the occipital artery (sulcus arteriae occipitalis). On the inner surface of the process there is a wide groove of the sigmoid sinus (sulcus sinus sigmoidei). The internal structure of the process is represented by cells, the largest of which is called the mastoid cave (antrum mastoideum).
Numerous canals and tubules pass through the temporal bone:
1) mastoid tubule (canaliculus mastoideus);
2) the tympanic tubule (canaliculus tympanicus);
3) the tubule of the drum string (canaliculus chordae tympani);
4) carotid-tympanic tubules (canaliculus caroticotympanici);
5) sleepy canal (canalis caroticus);
6) the facial canal (canalis facialis);
7) muscular-tubal canal (canalis musculotubarius).
TEMPORAL BONE
Temporal bone, os tempordle, a paired bone, has a complex structure, since it performs all 3 functions of the skeleton and not only forms part of the lateral wall and base of the skull, but also contains the organs of hearing and balance. It is the product of the fusion of several bones (mixed bone), independently existing in some animals, and therefore consists of three parts: 1) the scaly part, pars squamosa (in animals - os squamosum); 2) the drum part, pars tympanica (in animals, tympanicum), and 3) the stony part, pars petrosa (in animals, petrosum).
During the 1st year of life, they merge into a single bone, closing the external auditory meatus, meatus acusticus externus, in such a way that the scaly part lies above it, the stony part is inward from it, and the tympanic part is behind, below and in front. Traces of the fusion of individual parts of the temporal bone remain for life in the form of intermediate sutures, and cracks, namely: on the border of pars squamosa and pars petrosa, on the anteroposterior surface of the latter-fissura petrosquamosa, deep in the jaw fossa -fissura tympanosquamosa, which is divided by the process of the stony part on fissura petrosquamosa and fissura petrotympanica (the chorda tympani nerve leaves through it).
The scaly part, pars squamosa, is involved in the formation of the lateral walls of the skull. It belongs to the integumentary bones, that is, it ossifies on the soil of connective tissue and has a relatively simple structure in the form of an upright plate with a rounded edge superimposed on the corresponding edge of the parietal bone, margo squamosa, in the form of fish scales, hence its name.
On its cerebral surface, facies cerebralis, traces of the brain, digital impressions, impressiones digitatae, and an upward groove from a. meningea media. The outer surface of the scales is smooth, participates in the formation of the temporal fossa and is therefore called facies temporalis. The zygomatic process, processus zygomaticus, departs from it, which goes forward to connect with the zygomatic bone. At its beginning, the zygomatic process has two roots: anterior and posterior, between which there is a fossa for articulation with the lower jaw, fossa mandibularis. An articular tubercle, tuberculum articulare, is placed on the lower surface of the anterior root, which prevents the dislocation of the head of the lower jaw forward with a significant opening of the mouth.
The tympanic part, pars tympanica, of the temporal bone forms the anterior, lower and part of the posterior edge of the external auditory canal, ossifies endesmally and, like all integumentary bones, has the appearance of a plate, only sharply curved.
The external auditory meatus, meatus acusticus extern us, is a short canal that goes inward and somewhat forward and leads into the tympanic cavity. The upper edge of its outer opening, porus acusticus externus, and part of the posterior edge are formed by the scales of the temporal bone, and the rest of the length - by the tympanic part.
In a newborn, the external auditory canal has not yet been formed, since the tympanic part is an incomplete ring (anulus tympanicus), covered by the tympanic membrane. Due to such a close location of the tympanic membrane outwards, diseases of the tympanic cavity are more often observed in newborns and young children.
An important part of the temporal bone is the stony part, pars petrosa, so named for the strength of its bone substance, due to the fact that this part of the bone simultaneously participates in the base of the skull, and is the bony receptacle of the organs of hearing and balance, which have a very thin structure and need strong protection from damage. It develops on the basis of cartilage. The second name of this part is a pyramid, given by its shape of a triangular pyramid, the base of which is turned outward, and the top - forward and inward to the sphenoid bone.
The pyramid has three surfaces: front, back and bottom. The anterior surface is part of the bottom of the middle cranial fossa; the posterior surface faces posteriorly and medially and forms part of the anterior wall of the posterior cranial fossa; the lower surface faces downward and is visible only on the outer surface of the skull base. The external relief of the pyramid is complex and due to its structure as a receptacle for the middle (tympanic cavity) and inner ear (bony labyrinth, consisting of the cochlea and semicircular canals), as well as the passage of nerves and blood vessels. On the front surface of the pyramid, near its apex, there is a noticeable slight depression, impressio trigimini, from the trigeminal nerve node (n. Trigeminus). Outwardly from it there are two thin grooves, medial - sulcus n. petrosi majoris, and lateral-sulcus n. petrosi minoris. They lead to two similar holes: medial, hiatus canalis n. petrosi majoris, and lateral, hiatus canalis n. pe trosi minoris. Outside of these holes, an arcuate eminence, etineptia arcuata, is noticeable, formed due to the protrusion of a rapidly developing labyrinth, in particular the upper semicircular canal. The surface of the bone between eminentia arcuata and squama temporalis forms the roof of the tympanic cavity, tegmen tympani.
Approximately in the middle of the posterior surface of the pyramid is the internal auditory opening, porus acusticus internus, which leads to the internal auditory canal, meatus acdsticus internus, where the facial and auditory nerves pass, as well as the internal auditory artery and veins.
From the lower surface of the pyramid, facing the base of the skull, there is a thin pointed styloid process, processus styloideus, which serves as an attachment point for the muscles of the "anatomical bouquet" (mm. Styloglossus, stylohyoideus, stylopharyngeus), as well as ligaments - ligg. stylohyoideum and stylomandibulare. The styloid process is a part of the temporal bone of the branchial origin. Together with lig. stylohyoideum it is the remainder of the second visceral arch, the hyoid (hyoid).
Between the styloid and mastoid processes there is an awl-mastoid opening, foramen stylomastoideum, through which n comes out. facialis and one of the arteries enters. A deep jugular pit, fossa jugularis, is located medially from the styloid process. Anterior to the fossa jugularis, separated from it by a sharp crest, is the outer opening of the carotid canal, foramen caroticum externum.
The pyramid has three edges: front, back and top. The short anterior margin forms an acute angle with scales. In this corner, the opening of the musculoskeletal canal, canalis musculotubarius, leading to the tympanic cavity is noticeable. This canal is divided by a partition into two sections: upper and lower. The upper, smaller, semi-canal, semicanalis T. tensoris tympani, contains this muscle, and the lower, larger, semicatialis tiibae auditvae, is the bony part of the auditory tube, which serves to conduct air from the pharynx into the tympanic cavity.
A clearly visible groove, sulcus sinus petrosi superioris, runs along the upper edge of the pyramid dividing the anterior and posterior surfaces, a trace of the venous sinus of the same name.
The posterior edge of the pyramid anterior to the fossa jugularis connects with the main part of the occipital bone and forms, together with this bone, siilcus sinus petrosi inferioris - a trace of the inferior petrosal venous sinus.
The outer surface of the base of the pyramid serves as a place of muscle attachment, which determines its external relief (process, notches, roughness). Downward, it stretches into the mastoid process, processus mastoideus. Attached to it is the sternocleidomastoid muscle, which supports the head in the balance required when the body is upright. Therefore, the mastoid process is absent in tetrapods and even apes and develops only in humans in connection with his upright posture. On the medial side of the mastoid process there is a deep mastoid notch, incisura mastoidea, - the place of attachment of m. digastricus; even more inwards - a small furrow, sulcus a. occipitalis, - a trace of the artery of the same name.
On the outer surface of the base of the mastoid process, a smooth triangle is distinguished, which is a place for prompt access to the cells of the mastoid process when they are filled with pus.
Inside, the mastoid process contains these cells or cells, cellulae mastoideae, which are air cavities separated by bone crossbars, receiving air from the tympanic cavity, with which they communicate through the antrum mastoideum. On the cerebral surface of the base of the pyramid, there is a deep groove, sulcus sinus sigmoidei, where the venous sinus of the same name lies.
Temporal bone canals. The largest canal is canalis caroticus, through which the internal carotid artery passes. Starting with its outer opening, foramen caroticum externum, on the lower surface of the pyramid, it rises upward, then bends at a right angle and opens with its internal opening, foramen caroticum internum, at the top of the pyramid medially from canalis musculotubarius. The canal of the facial nerve (Fig. 27), canalis facialis, begins deep in the porus acusticus internus, from where the canal first goes forward and laterally to the cracks (hiatus) on the front surface of the pyramid; at these holes, the canal, while remaining horizontal, turns at a right angle laterally and backward, forming a bend - a knee, geniculum canalis facialis, and then goes down and ends through the foramen stylomastoideum, located on the lower surface of the temporal bone pyramid.
Os temporale, steam room, participates in the formation of the base of the skull and the lateral wall of its vault. It contains the organ of hearing and balance. It articulates with and is the support of the chewing apparatus.
On the outer surface of the bone there is an external auditory opening, porus acusticus externus, around which there are three parts of the temporal bone; above - a scaly part, inwardly and behind - a stony part, or a pyramid, in front and below - a drum part.
The scaly part, pars squamosa, has the shape of a plate and is located almost in the sagittal direction. The outer temporal surface, facies temporalis, of the scaly part is slightly rough and slightly convex. In the posterior part, the groove of the middle temporal artery, sulcus arteriae temporalis mediae (the trace of the adhesion of the artery of the same name) runs in the vertical direction.
In the posterior lower part of the scaly part, an arcuate line passes, which continues into the lower temporal line, linea temporalis inferior,.
From the scaly part, above and somewhat anterior to the external auditory opening, the zygomatic process, processus zygomaticus, departs in a horizontal direction. It is, as it were, a continuation of the supra-mastoid ridge, crista supramastoidea, located horizontally along the lower edge of the outer surface of the scaly part. Starting with a broad root, the zygomatic process then narrows. It has an inner and outer surface and two edges - a longer top and bottom, shorter. The anterior end of the zygomatic process is serrated. The zygomatic process of the temporal bone and the temporal process, processus temporalis, the zygomatic bone are connected using the temporomandibular suture, sutura temporozygomatica forming a zygomatic arch, arcus zygomaticus.
On the lower surface of the root of the zygomatic process is a transverse-oval mandibular fossa, fossa mandibularis. The anterior half of the fossa, up to the stony-scaly fissure, is the articular surface, fades articularis, of the temporomandibular joint. In front, the mandibular fossa is limited by the articular tubercle, tuberculum articulare.
The outer surface of the scaly part is involved in the formation of the temporal fossa,
fossa temporalis (beams begin here, m. temporalis).
The inner brain surface, facies cerebralis, is slightly concave. It has finger-like indentations, impressiones digitatae, as well as an arterial groove, sulcus arteriosus (it contains the middle meningeal artery, a. Meningea media).
The scaly part of the temporal bone has two free edges - the sphenoid and the parietal.
The antero-inferior wedge-shaped edge, margo sphenoidalis, wide, serrated, connects to the scaly edge of the large wing of the sphenoid bone and forms a wedge-scaly suture, sutura sphenosquamosa.
The superior posterior parietal margin, margo parietalis, is pointed, longer than the previous one, connected to the scaly edge of the parietal bone.
The pyramid (stony part), pars petrosa, of the temporal bone consists of the posterolateral and anteromedial sections.
The posterolateral part of the petrous part of the temporal bone is the mastoid process, processus mastoideus, which is located posterior to the external auditory opening. It distinguishes between the outer and inner surfaces. The outer surface is convex, rough and is the site of muscle attachment. Downward, the mastoid process turns into a cone-shaped protrusion, which is well felt through the skin,
On the inside, the process is limited by a deep mastoid notch, incisura mastoidea (the posterior abdomen of the digastric muscle originates from it, venter posterior m. Digastrici). Parallel to the notch and somewhat posteriorly, there is a groove of the occipital artery, sulcus arteriae occipitalis (a trace of the adhesion of the artery of the same name).
On the inner, cerebral, surface of the mastoid process, there is a wide S-shaped groove of the sigmoid sinus, sulcus sinus sigmoidei, passing at the top into the groove of the parietal bone of the same name and further into the groove of the transverse sinus of the occipital bone (the venous sinus, sinus transversa, lies in it). Downward, the sigmoid sinus groove continues as the eponymous groove of the occipital bone.
The posterior border of the mastoid process is the serrated occipital margin, margo occipitalis, which, connecting with the mastoid margin of the occipital bone, forms the occipital-mastoid suture, sutura occipitomastoidea. In the middle of the length of the suture or in the occipital edge there is a mastoid opening, foramen mastoideum (sometimes there are several of them), which is the location of the mastoid veins, vv. emissariae mastoidea, connecting the saphenous veins of the head with the sigmoid venous sinus, as well as the mastoid branch of the occipital artery, ramus mastoideus a. occipitalis.
Above, the mastoid process is bounded by the parietal edge, which, on the border with the same edge of the scaly part of the temporal bone, forms a parietal notch, incisura parietalis; it includes the mastoid angle of the parietal bone, forming the parieto-mastoid suture, sutura parietomastoidea.
At the place of transition of the outer surface of the mastoid process to the outer surface of the scaly part, you can see the remnants of the scaly-mastoid suture, sutura squamosomastoidea, which is well pronounced on the skull of children.
On the cut of the mastoid process, the bony air cavities inside it are visible - mastoid cells, cellulae mastoideae. These cells are separated from one another by the bony mastoid walls, paries mastoideus. The permanent cavity is the mastoid cave, antrum mastoideum, in the central part of the process; mastoid cells open into it, it connects to the tympanic cavity, cavitas tympanica. The mastoid cells and the mastoid cavity are lined with mucous membranes.
The anteromedial part of the stony part lies medially from the scaly part and the mastoid process. It has the shape of a triangular pyramid, the long axis of which is directed from the outside and back to front and medially. The base of the stony part faces outwards and backwards; the top of the pyramid, apex partis petrosae, is directed inward and anteriorly.
In the stony part, three surfaces are distinguished: anterior, posterior and lower, and three edges: upper, posterior and anterior.
The front surface of the pyramid, facies anterior partis petrosae, is smooth and wide, facing the cranial cavity, directed obliquely from top to bottom and in front and passes into the brain surface of the scaly part. It is sometimes separated from the latter by a stony-scaly gap, fissura petrosquamosa. Almost in the middle of the anterior surface there is an arcuate eminence, eminentia arcuata, which is formed by the anterior semicircular canal of the labyrinth lying beneath it. Between the elevation and the stony-scaly gap, there is a small platform - the roof of the tympanic cavity, tegmen tympani, under which is the tympanic cavity, cavum tympani. On the front surface, near the apex of the stony part, there is a small trigeminal depression, impressio trigemini (the place where the trigeminal node fits, ganglion trigeminale).
Lateral to the impression is the cleft of the canal of the large stony nerve, hiatus canalis n. petrosi majoris, from which a narrow groove of the large stony nerve, sulcus n. petrosi majoris. Anteriorly and somewhat laterally from the indicated opening, there is a small cleft of the canal of the small stony nerve, hiatus canalis n. petrosi minoris, from which the groove of the small stony nerve, sulcus n. petrosi minoris.
The posterior surface of the pyramid, facies posterior partis petrosae, as well as the front, faces the cranial cavity, but goes up and posteriorly, where it passes into the mastoid process. Almost in the middle of it there is a round internal auditory opening, porus acusticus internus, which leads to the internal auditory canal, meatus acusticus internus (it contains the facial, intermediate, vestibular cochlear nerves, nn.facialis, intermedius, vestibulocochlearis, as well as an artery and the vein of the labyrinth, a. et v. labirinthi). Slightly higher and lateral from the internal auditory foramen there is a well-defined, small depth subarc fossa, fossa subarcuata in newborns (it includes the process of the dura mater of the brain). Even more laterally lies the slit-like outer aperture of the vestibule aqueduct, apertura externa aqueductus vestibuli, opening into the vestibule aqueduct, aqueductus vestibuli. Through the aperture, the endolymphatic duct emerges from the inner ear cavity.
The lower surface of the pyramid, facies inferior partis petrosae, rough and uneven, forms part of the lower surface of the base of the skull. On it is a rounded or oval jugular fossa, fossa jugularis (the place where the upper bulb of the internal jugular vein fits).
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